Final answer:
Edema is caused by damage to blood or lymphatic vessels, a decrease in osmotic pressure due to a liver's inability to produce enough plasma proteins, and by other conditions like inflammation. Albumin deficiency also leads to edema by disrupting the osmotic balance, causing fluid accumulation. Edema can be diagnosed by the 'pitting' test.
Step-by-step explanation:
Edema, or the accumulation of excess water in the tissues, can be caused by several physiological factors. One common cause of edema is damage to blood vessels and/or lymphatic vessels, which leads to water leakage from blood capillaries into the surrounding tissues. Additionally, edema can also be due to a decrease in osmotic pressure in cases of chronic and severe liver disease. This occurs when the liver is unable to manufacture enough plasma proteins, leading to a decrease in colloid osmotic pressure that normally counterbalances hydrostatic pressure in the capillaries, thus causing water loss into the tissues. Disorders like inflammation can also increase the permeability of blood vessels, further contributing to the development of edema.
The deficiency of albumin, the major protein that regulates water content in the tissues, is another factor that leads to edema. Albumin maintains the osmotic balance between blood vessels and tissues. Without adequate albumin, fluid accumulates, causing swelling.
Edema is often identified by symptoms such as swollen subcutaneous tissues, an increase in the limb's size, and stretched tight skin. One diagnostic method for detecting edema, particularly 'pitting' edema, is by pressing a finger into the swollen area and observing whether the depression persists for several seconds after the finger is removed.